import java.io.*;
import java.util.*;

public class mortgage {
    StringTokenizer st = new StringTokenizer("");
    BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

    public static void main(String[] args) throws Exception {
        mortgage inst = new mortgage();
        while(inst.run()) {}
    }

    
    public boolean run() throws Exception {
        double debth = nextDouble();
        int monthPayment = nextInt();
        int monthCount = nextInt();
        double interest = nextDouble();
        if(debth==0&&monthPayment==0&&monthCount==0&&interest==0) return false;
        interest /= 1200;
        monthCount *=12;
        boolean success= false;
        while(monthCount>0) {
            //System.out.println(debth);
            debth += debth*(interest);
            debth -= monthPayment;
            monthCount--;
            if(debth<=0) {
                success = true;
                break;
            }
        }
        
        if(success) System.out.println("YES");
        else System.out.println("NO");
        return true;
    }
    
    public String nextToken() throws Exception {
        while(!st.hasMoreTokens()) st = new StringTokenizer(br.readLine());
        return st.nextToken();
    }
    
    public int nextInt() throws Exception {
        return Integer.parseInt(nextToken());
    }
    
    public double nextDouble() throws Exception {
        return Double.parseDouble(nextToken());
    }
}